Sensitive Single-beam Heterodyne CARS Microscopy with Independently Phase Controlled Local Oscillator

In this paper we have developed a single-beam heterodyne CARS. In a single-beam CARS-scheme, all CARS frequencies are provided within the spectrum of a broadband laser pulse with femtosecond pulse shaping ensuring spectral resolving power. Without complicating the single-beam setup in any way, we have introduced interferometric detection by not only controlling the CARS signal generation with the pulse shaper, but by also using it to generate a phase-controlled local oscillator field at the CARS signal wavelengths.